Industrial bottle filling processes typically require high performance capital equipment. This equipment must be highly reliable, compact, low cost, low maintenance, and precise. A typical apparatus for filling large volumes of bottles in such environments includes a filler valve to reliably fill bottles with a high accuracy of less than 1% of the fill volume in a matter of few seconds in a clean process without spill. Fast filling is required for high throughput and fast payback of capital investment. Cleanliness is needed to meet increasingly stringent health standards, in particular when dealing with dairy fluids. In this case, any spills may develop harmful bacteria in the filling system environment, which in turn may violate health standards.
Filling accuracy is important for cost control. A lower than advertised fill weight may violate weight and measure laws. Overfill, which is often done to avoid violations, results in material waste and overflow spill. Compactness is needed to lower the filling system size and reduce its footprint. Finally, a low cost for a single valve is required since a typical high performance filling system may have well over hundred filler valves.
Thus, the main problem in the general requirements of a high performance valve, for a bottle filling system, is the following conflicting demands: 1) High filling rate; and 2) High filling precision.
One possible solution towards satisfying these requirements is to use a single stage pinch valve. A single stage pinch valve assembly typically contains an elastic tube, through which the filling fluid flows. The elastic tube is installed within a solid tube. When air, or other actuator, is applied between the inner surface of the solid tube and the outer surface of the elastic tube, the elastic tube is compressed to close the fluid flow passage, thereby stopping the flow of fluid through the valve.
EP2682652 discloses a pinch valve that has a deformable tubular valve element, which defines a main fluid flow channel. A rigid tube is also provided within the main channel for providing a second fluid flow channel. An actuating structure is provided to deform the valve element to alternately open and close the main fluid flow channel. To close the main fluid flow channel, the tubular valve is deformed to fit closely against a valve seat surface provided on the outer surface of the rigid tube. While this valve allows the flow of two fluids, there are no provisions provided for stopping the flow of the second fluid flow channel within the rigid tube.
While such valves are compact and low cost, they do not solve the conflict between high filling rate and high fill height precision. Such valves can also generate either slow flow at high accuracy or high flow at a lower accuracy.
Another solution is a mechanically actuated valve. A cam-operated mechanism raises the empty bottle so that the neck of the bottle is sealed against the valve and a ball check valve is the only passage for venting air from the bottle while fluid fills it up. The rising fluid level in the bottle reaches the ball float and raises it to close the vent, hence closing the flow of fluid. One typical problem with this solution is low reliability due to possible mechanical failure of the cam mechanism, and mechanical valve. Another problem is fluid spillage inherent in vent-controlled filling with mechanical valves resulting in fluid wasted as much as 6% of fill volume and providing a good breeding ground for bacterial growth.
There is therefore a need to improve the design of prior art filling system valves.